'use strict';
var crypto = require('crypto');
var fs = require('fs');
var http = require('http');

var utils = {};

/**
 * Base64 encode / decode
 * http://www.webtoolkit.info/
 **/

utils.Base64 = {
    // private property
    _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
    // public method for encoding
    encode: function(input) {
        var output = "";
        var chr1;
        var chr2;
        var chr3;
        var enc1;
        var enc2;
        var enc3;
        var enc4;
        var i = 0;
        input = this._utf8_encode(input);
        while (i < input.length) {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);
            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;
            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }
            output = output +
                this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
                this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
        }
        return output;
    },
    // public method for decoding
    decode: function(input) {
        var output = "";
        var chr1;
        var chr2;
        var chr3;
        var enc1;
        var enc2;
        var enc3;
        var enc4;
        var i = 0;
        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        while (i < input.length) {
            enc1 = this._keyStr.indexOf(input.charAt(i++));
            enc2 = this._keyStr.indexOf(input.charAt(i++));
            enc3 = this._keyStr.indexOf(input.charAt(i++));
            enc4 = this._keyStr.indexOf(input.charAt(i++));
            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;
            output = output + String.fromCharCode(chr1);
            if (enc3 != 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) {
                output = output + String.fromCharCode(chr3);
            }
        }
        output = this._utf8_decode(output);
        return output;
    },
    // private method for UTF-8 encoding
    _utf8_encode: function(string) {
        string = string.replace(/\r\n/g, "\n");
        var utftext = "";
        for (var n = 0; n < string.length; n++) {
            var c = string.charCodeAt(n);
            if (c < 128) {
                utftext += String.fromCharCode(c);
            } else if ((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            } else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }
        }
        return utftext;
    },
    // private method for UTF-8 decoding
    _utf8_decode: function(utftext) {
        var string = "";
        var i = 0;
        var c;
        var c2;
        var c3;
        c = c2 = 0;
        while (i < utftext.length) {
            c = utftext.charCodeAt(i);
            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            } else if ((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i + 1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            } else {
                c2 = utftext.charCodeAt(i + 1);
                c3 = utftext.charCodeAt(i + 2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }
        }
        return string;
    }
};

utils.md5sum = function(data) {
    var md5 = crypto.createHash('md5');
    md5.update(data, 'utf8');
    return md5.digest('hex');
};

utils.md5sumFile = function(fpath, callback) {
    var md5 = crypto.createHash('md5');
    var rs = fs.createReadStream(fpath);
    rs.on('data', function(d) {
        md5.update(d);
    });
    rs.on('end', function() {
        return callback(null, md5.digest('hex'));
    });
};

utils.makeSign = function(method, uri, date, length, password, operator) {
    if (uri.indexOf('?') >= 0) {
        uri = uri.split('?')[0];
    }
    var sign = method + '&' + uri + '&' + date + '&' + length + '&' + utils.md5sum(password);
    return 'UpYun ' + operator + ':' + utils.md5sum(sign);
};

utils.genReqOpts = function(thisArg, method, remotePath, length, custom) {
    var headers = custom || {};
    var date = (new Date()).toGMTString();

    if (remotePath.indexOf('/') !== 0) {
        remotePath = '/' + remotePath;
    }

    // preifx remotePath sub dir with '/' if not exists
    var t = remotePath.split(thisArg._conf.bucket);
    if (t.length >= 2 && t[1] !== undefined && t[1].indexOf('/') !== 0) {
        t[1] = '/' + t[1];
    }
    remotePath = t.join(thisArg._conf.bucket);

    var contentLength = length || 0;
    headers['Content-Length'] = contentLength;
    headers.Date = date;
    headers.Authorization = utils.makeSign(method, remotePath, date, contentLength, thisArg._conf.password, thisArg._conf.operator);
    headers.Host = thisArg._conf.endpoint;
    headers['User-Agent'] = 'UPYUN Node SDK v' + thisArg._conf.version;

    var opts = {
        hostname: thisArg._conf.endpoint,
        method: method,
        path: remotePath,
        headers: headers
    };

    return opts;
};

utils.parseRes = function(res) {
    if (res.statusCode >= 400) {
        res.data = JSON.parse(res.data || '{}');
    }

    return res;
};

utils.request = function(options, fileToUpload, fileDownloadTo, callback) {
    var resData = '';

    var req = http.request(options, function(res) {
        if (fileDownloadTo) {
            var ws = fs.createWriteStream(fileDownloadTo);
            res.pipe(ws);
            ws.on('finish', function() {
                callback(null, {
                    statusCode: res.statusCode,
                    headers: res.headers,
                    data: resData
                });
            });
        } else {
            res.setEncoding('utf8');
            res.on('data', function(chunk) {
                resData += chunk;
            });
            res.on('end', function() {
                callback(null, {
                    statusCode: res.statusCode,
                    headers: res.headers,
                    data: resData
                });
            });
        }
    });

    if (fileToUpload && fs.existsSync(fileToUpload)) {
        var rs = fs.createReadStream(fileToUpload);
        rs.pipe(req, {
            end: false
        });
        rs.on('close', function() {
            req.end();
        });
    } else if (fileToUpload) {
        req.write(fileToUpload);
        req.end();
    } else {
        req.end();
    }

    req.on('error', function(err) {
        callback(err);
    });
};

module.exports = exports.utils = utils;